Planetary Gear Train for Automatic Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automatic transmissions with increased shift stages face challenges in installability, production cost, weight, and power flow efficiency due to the need for more parts, which complicates achieving better fuel consumption and drivability.
Innovation Solution
A planetary gear train design with four single pinion planetary gear sets and six engagement elements, including clutches and brakes, is used to achieve at least ten forward speeds and one reverse speed, optimizing the arrangement of shafts and engagement elements to improve shift stages and engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption and drivability are improved, but the installability deteriorates and the transmission becomes lengthy
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission assembly, merging their functions to achieve ten forward speeds without requiring separate transmissions. This consolidation improves installability while maintaining the fuel efficiency benefits of multiple shift stages
Solution Approach 2:
The planetary gear sets are designed with multi-functionality, where each gear set can serve multiple purposes across different speed ranges. The engagement elements (clutches and brakes) are configured to control multiple gear sets simultaneously, allowing a single transmission assembly to provide both the fuel consumption improvement of ten forward speeds and the installability benefit of a compact design
2Productivity
If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption is improved, but the production cost increases
Solution Approach 1:
The patent merges four planetary gear sets into one integrated assembly, reducing the total number of separate components that would need to be manufactured and assembled. This consolidation lowers production costs while maintaining the ten forward speed capability that improves fuel consumption
Solution Approach 2:
The transmission is segmented into four distinct planetary gear sets, each optimized for specific speed ranges. This segmentation allows for standardized manufacturing of modular components that can be produced efficiently and assembled into the complete transmission, reducing overall production costs
3Productivity
If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption is improved, but the weight increases
Solution Approach 1:
The patent combines multiple planetary gear sets into a single integrated transmission assembly, consolidating their weight into one compact unit. This merging reduces the total weight compared to having separate transmissions while maintaining the ten forward speed capability that improves fuel consumption
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where components of different gear sets are interlocked and share common mounting structures. This nesting minimizes the overall volume and weight of the transmission assembly while providing the fuel efficiency benefits of multiple shift stages
4Productivity
If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption is improved, but the power flow efficiency deteriorates
Solution Approach 1:
The patent employs dynamic control of engagement elements (clutches and brakes) to optimize power flow through different planetary gear sets based on operating conditions. This dynamic engagement strategy minimizes energy losses by selecting the most efficient power transmission path for each speed range, maintaining high power flow efficiency while achieving ten forward speeds for improved fuel consumption
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances driving stability, maximizes engine efficiency, and improves power delivery performance while reducing fuel consumption by simplifying the number of parts and improving shift feel.
Implementation Method 1
a first planetary gear set having first, second and third rotation elements, a second planetary gear set having fourth, fifth, and sixth rotation elements, a third planetary gear set having seventh, eighth, and ninth rotation elements, and a fourth planetary gear set having tenth, eleventh, and twelfth rotation elements
Data Source
AI summary
A planetary gear train may include input and output shafts, first to fourth planetary gear sets respectively having first to third, fourth to sixth, seventh to ninth, and tenth to twelfth elements, a first shaft connected to the first, sixth, and seventh elements, and selectively connected to the input shaft, a second shaft connected to the ninth element and selectively connected to the input shaft, a third shaft connected to the eleventh element and the output shaft, a fourth shaft connected to the third and fourth elements, a fifth shaft connected to the fifth, eighth, and twelfth elements, and a plurality of shafts each selectively connecting a corresponding element to a transmission housing, the corresponding element being an element of the first and fourth planetary gear sets which is not interconnected.